Obesity levels are increasing dramatically in research animals and others living close to humans

It is a known fact that dramatic increase in obesity has occurred among humans within the last several decades.  I was fascinated to read in the journal Proceedings of the Royal Society B. about the increasing levels of obesity  in research animals and others living close to humans.

David Allison, a statistical geneticist at the University of Alabama, Birmingham, and his colleagues gathered data on body weights of more than 20,000 adult animals from 24 populations of 8 different species from around North America. All 24 populations of animals, which ranged from primates housed in research facilities to feral rats living in the greater Baltimore area, showed measurable increase in body weight.

Average body weights of captive chimpanzees increased at a rate of 33 percent each decade. It was 9 percent per decade in captive marmosets. Laboratory mice got 12 percent increase  every ten years. The average weight of cats increased by almost 10 percent each decade, while dogs' weights increased by 3 percent every decade.

In 23 out of the 24 populations animals were not just overweight, they were plain obese. Read this against the fact that records of exactly what research animals were fed and their housing conditions haven't changed much in the past 50 years.

Scientists suspect that Environmental toxins and viruses could be the causative factors for the aberration. Endocrine disruptors such as bisphenol A (BPA) and some tin-containing compounds have been shown to increase body mass. Adenovirus, have also been linked to significantly increased body mass.